Complex compounds of the platinum group as photographic fog inhibitors



Patented Aug. 28, 1951 COMPLEX COMPOUNDS OFFITTH'ELPLATINIM GROUP A PHOTOGRZALRHIG; FOG IN- HIBITOBS Adrian PetenH: Trivelli and1 Wiiliam Smith",

Rochester, NaYi, assignorsto Eastman Kodak Com'pany,.-Rochester, N. Y2", a corporation of New-J rsey No Drawing.1 AppiicationiAlugust 2. 1947. v

Serial No. 765,818,

This invention relates to fogwinhibiting agents and stabilizers for' photographlc emulsionsand to photographic emulsions containing: them.-

This application is a continuation-in-part of our application Serial No. 613,700, filed August 30, 1945, now abandoned.

It is known that photographic-emulsions; par' ticularly ultra-sensitive emulsions orthose con-- taining coloring sensitizers exhibit: a tendency to form a deposit of silver in the emulsionr This deposit extends more orless uniformly overthe entire emulsion and is known as fog. Photo- 11 Claims, (01. 95-7) graphic fog is of two types: Eocal' andgeneralt Local fog is formed by exposure 01? the-film or: plate at undesired points aszby a little leak in General fog or as itris sometimes known chemical fog is formed in anumber of;

the camera.

ways. It may be caused by the conditions under. which the film or plateisstored such, as conditions of high temperature or humidity or unusually long time off storage. The, nature. of the emulsion may also produce chemicalffogjas well as the conditions of development ofgthe emulsion as by development for protracted periods of time or at temperaturesabove normal;

Highly sensitive emulsions are more lilgely to fog than those of lower sensitivity. We are pri marily concerned with general orchemical fog.

General fog and loss, of sensitivity of the emulsion are especially likely to occur when the sensitive material is stored under conditions other than ideal, that is, under; conditions of ,high temperature and, humidity as in tropical.

regions.

It is an object of the invention to provide novel anti-fogging or fog-inhibiting compounds for emulsions, A further objectis to provide anti-fogging agents which stabilizezthe initial,

sensitivity of the emulsion. lAstilllxfurthernobiject is to provide anti-fogging agents which, improve the keeping of the-emulsion-in tropical: regions. Other objectswill appear {from the fol-:.

lowing description of our inventiom These objects are accomplished by incorporating in-a' silver halide emulsion, o v$ 13 i illcbing layer or "overcoating layer contiguous to. adja ladate, (NH4)z(PdCls);

cent to, or' in contact; with, said emulsion, an acid or a' salt having the general formula:

azcMxa) n. :..w ich R is hydrogen or an alkali metal.

M is a metal of the-platinum group other than osmium.

X is a halogen atom.

Compounds suitable foruse according to our invention are those of theabove general formula in which R is, hydrogen, ammonium or an alkali metal such as sodium or potassium, M is a metal of the platinum group such as platinum; iridium,

palladium, rhodium or ruthenium and. X is a,

halogen atom such. as chlorine or bromine; Suitable compounds are ammonium chloropalammonium chlororhodate,v (NI-I4) zRhCls; ammonium, chlororuthenate, (NHQaQRuCls) ammonium chloroplatinate,

ammonium .bromopalladate, (NHi) 2(PdBra) and ammonium I chloroiridate, (NH4)'z(Ir.C.lc) Com.-

pounds of osmium cause, desensitization and produce no fog-inhibiting effect.

Theobject of our invention is to maintain the sensitivity and fog. of 7 silver halide, emulsions. at

or closeto initial optimum values under keeping conditionsof high temperature and humidity. The fog inhibitors which we propose to use are added to. the emulsion, during the. process of manufacture to avoid loss, of sensitivity and to inhibit the growth of chemical fog with passage of time under non-ideal conditions of storage.

" A solution of ammonium chloropalladate when.

added in suitable concentration before-coating to unsensitized or optically sensitized photographic. emulsions does not afiect the, 361151110: metric values for sensitivity and fog when measurements-are made soon after coating. When. sensitometric measurements are made after an.- preciable intervals of time under tropical or dry conditions of storage at elevated temperatures, howeyer, 'thisxcoinpound' does stabilize photo.- graphic speed and'maintain fog at a low level:

The preparation. of silver halide emulsions involves three separate operations (1) the emulsiflcation and digestion or ripening of the silver halide (2) the freeing of the emulsion from excess soluble salts usually by washing, (3) the second digestion or after-ripening to obtain increased sensitivity. (Mees. The Theory of the Photographic Process, 1942.) We prefer to add the fog-inhibiting agents after the final digestion or after-ripening, although they may be added before digestion. The most useful concentration range of fog inhibitor is from 0.25 to 3.90 grams of fog inhibitor per kilogram of silver nitrate converted to silver halide.

The anti-foggant and stabilizing action was determined by incubation of the emulsions under simulated tropical conditions and also by incubation in dry heat at 120 F. for various lengths of time from 6 days to one month. The results a i of these tests are tabulated here and are compared with the initial speed, gamma and fog of the emulsions with and without the anti-foggant and stabilizing compound. The tests from which the following tabulation was made used a highspeed negative silver halide emulsion exposed on an Eastman type 13 sensitometer and developed for five minutes in a developer of the following composition Grams Monomethyl paraminophenol sulfate 2.5 Sodium suliite (desiccated) 30 I-Iydroquinone 2.5 Sodium metaborate 10 Potassium bromide 0.5'

Water to one liter The results are as follows:

' in the emulsion layer.

ammonium chlororhodate. A coating of highspeed negative emulsion was exposed on a type IIB sensitometer and developed for five minutes Grams perk of AKNOI f 111 10 1' F 10/1 em on speed Gamma g Speed Gamma Fog 795 1. 41 .11 172 l. 88 12 542 1. 44 205 1. 71 .08 400 1. 37 08 280 l. 58 06 255 1. 4B 07 270 l. 48 07 760 1. 57 12 120 l 51 13 In addition to'their use in a sensitive emulsion layer the fog inhibiting agents of our invention may be incorporated in a subbing layer or overcoating. layer contiguous to, adjacent to, or in contact with, said sensitive emulsion layer. When used in this Way, the fog-inhibiting agents stabilize the. sensitive emulsion when the photographic element is kept for long periods of time under conditions of high temperature or humidity or both, in the same way as when the agents are used in the sensitive emulsion itself. The

fog inhibiting-agents of our invention, when used a in a. layer such as a gelatin layer contiguous to the sensitive emulsion layer, are used in the same amounts as they would be used, if incorporated In other .words, the amount of fog inhibitorper unit area of the subbing layer or overcoating layer should be the Original 6 days at 120 F. 12 days at 120 F. g 1 mo. tropical (NHdrPdClo grams perdkg. of flgNOs 1/ 1/ 1/ use in emu sion 1 i 1 speed Gamma Fog speed Gamma Fog peed Gamma Fog Speed Gamma Fog One of the advantages of our invention is the fact that compounds such as ammonium chloropalladate may be prepared in a very high state of purity (Gilchrist, Chemical Reviews, vol. 30,

June 1943, page 307). Another and perhaps chief advantage is the greater extent of stabilizing action over a wide range of climatic conditions;

Similar data were obtained from a coating of V gelatino-silver halide emulsion containing ammonium chloroiridate. Plates containing varying amounts of the compound were exposed on a type IIB sensitometer and developed for five minutes in the same developer as before. results were as follows:

The

s ame,,per' kilogram of silver nitrate used in malt-.1

' ing the emulsion, as would be used in the same or overcoating. layer with an emulsion coated in the same waybutcontaining no fog inhibitor.

The following. table illustrates the incorporation of ammpnium chloropalladate in a gelatin layer coated over a negative type gelatino silver Original (N114): IrOls Grams/ 12 days at 120 F'.

1 mo. tropical Q i 3 mo. regular keeping kg. of .iXgNOQ used 10/ s 111 emu sion 1' i 10 i Gamma Fog Speed Gamma Fog Speed Gamma Fog Spa/ed Gamma Fog 1. 52 .10 455 1. 5a .46 e 265 1.59 16 525 1. .11 1. .11 I ,610 1. B2 .22 i 415 1. 2B 12 605 1. 55 11 l. 57 .11 560 1. 20 368 l. 49 14 630 1. 48 I 12 1. El .09 660 1. 52 390 1. '16 11 480 1. 64 .09

The following data were obtained from a coathalide emulsion l er'l the emulsion being exposed ing" of gelatino-silver halide emulsion containing: Quad sensitometer and devel-- oped for five minutes in the same developer as before:

Original '(NHO: PC1015 Grams 12 days at 120 F.

1 mo. tropical 2 mos. tropical per kg. of AgNOs used in emulsion l/i l/i l/i 1 i gpeed Gamma Fog speed Gamma Fog Speed Gamma Fog Sped Gamma Fog 165 1.03 .02 65 .79 .ll 61 .82 .ll 41 .90 .25 160 0. 94 .03 96 .80 .08 105 86 .04 82 .90 .07 170 1. 01 03 98 86 06' 126 88 03 B4 87 07 I The fog inhibiting agents which we have described may be used in various kinds of photographic emulsions. In addition to being useiul in ordinary non-sensitized emulsions they may also be used in ortho-chromatic, panchromatic and X-ray emulsions. If used with sensitizing dyes, they ma-y be added to the emulsion before or after the dyes are added. Various silver salts may be used as the sensitive salt such as silver bromide, silver iodide, silver chloride and mixtures of these. The dispersing agents may be gelatin or other colloid such as collodion, albumen, cellulose organic derivatives or synthetic resins.

It will be understood that we contemplate as included within our invention all modifications and equivalents falling Within the scope of the appended claims.

We claim:

1. A stabilized halide emulsion containing silver halide as the sole sensitive ingredient and containing from 0.25 gram to 3.9 grams per kilogram of silver nitrate of a compound having the structure Rama) where M is a metal of the platinum group other than osmium, X is a halogen atom, and R. is selected from the group consisting of hydrogen, ammonium and alkali metals.

2. A stabilized gelatino-silver halid emulsion containing silver halide as the sole sensitive ingredient and containing from 0.25 gram to 3.9 grams per kilogram of silver nitrate of a salt having the structure R2 (PdCls) where R is selected from the group consisting of an alkali metal and ammonium.

3. A stabilized silver halide emulsion containing silver halide as the sole sensitive ingredient and containing from 0.25 gram to 3.9 grams per kilogram of silver nitrate of ammonium chloropalladate.

4. A stabilized silver halide emulsion containing silver halide as the sole sensitive ingredient and containing approximatel 1.8 grams per kilogram of silver nitrate of ammonium chloropalladate. V

5. A stabilized silver halide emulsion containin silver halide as the sole sensitive ingredient and containing from 0.25 gram to 3.9 grams per kilogram of silver nitrate of a salt having the structure where R is selected from the group consisting of an alkali metal and ammonium.

6. A stabilized gelatino-silver halide emulsion containing silver halide as the sole sensitive ingredient and containing from 0.25 gram to 3.9

'7. A stabilized gelatino-silver halide emulsion containing silver halide as the sole sensitive ingredient and containing from 0.25 gram to 3.9 grams per kilogram of silver nitrate of ammonium chlororhodate.

8. A sensitive photographic element comprising a stabilized silver halide emulsion layer containing silver halide as the sole sensitive ingredient and a gelatin layer contiguous to said emulsion layer, one of said layers containing, per unit area of said layer, from 0.25 gram to 3.9 grams per kilogram of silver nitrate used in making the emulsion in the same unit area of said layer, of a compound having the structure where M is a metal of the platinum group other than osmium, X is a halogen atom, and R is selected from the group consisting of hydrogen, ammonium, and alkali metals.

9. A sensitive photographic element comprising a stabilized silver halide emulsion layer contain ing silver halide as the sole sensitive ingredient and a gelatin la er contiguous to said emulsion layer, one of said layers containing, per unit area of said layer, from 0.25 gram to 3.9 grams per kilogram of silver nitrate used in making the emulsion in the same unit area of said layer, of ammonium chloropalladate.

10. A sensitive photographic element comprising a stabilized silver halide emulsion layer containing silver halide as the sole sensitive ingredient and a gelatin layer contiguous to said emulsion layer, one of said layers containing, per unit area of said layer, from 0.25 gram to 3.9 grams per kilogram of silver nitrate used in making the emulsion in the same unit area of said layer, of ammonium chloroiridate.

11. A sensitive photographic element comprising a stabilized silver halide emulsion layer containing silver halide as the sole sensitive ingredient and a gelatin layer over and in contact with said emulsion layer, said gelatin overcoating layer containing, per unit area of said gelatin layer, from 0.25 gram to 3.9 grams per kilogram of silver nitrate used in making the emulsion in the same unit area of said gelatin layer, of ammonium chloropalladate.

ADRIAN P. H. TRIVELLI. WILLIAM F. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,120,429 Willis Dec. 8, 1914 1,120,580 Willis Dec. 8, 1914 

1. A STABILIZED HALIDE EMULSION CONTAINING SILVER HALIDE AS THE SOLE SENSITIVE INGREDIENT AND CONTAINING FROM 0.25 GRAM TO 3.9 GRAMS PER KILOGRAM OF SILVER NITRATE OF A COMPOUND HAVING THE STRUCTURE 